/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.messaging.tcp.reactor;

import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.List;

import io.netty.buffer.ByteBuf;

import org.springframework.messaging.Message;

/**
 * Convenient base class for {@link ReactorNettyCodec} implementations that need
 * to work with NIO {@link ByteBuffer}s.
 *
 * @author Rossen Stoyanchev
 * @since 5.0
 */
public abstract class AbstractNioBufferReactorNettyCodec<P> implements ReactorNettyCodec<P> {

    @Override
    public Collection<Message<P>> decode(ByteBuf inputBuffer) {
        ByteBuffer nioBuffer = inputBuffer.nioBuffer();
        int start = nioBuffer.position();
        List<Message<P>> messages = decodeInternal(nioBuffer);
        inputBuffer.skipBytes(nioBuffer.position() - start);
        return messages;
    }

    @Override
    public void encode(Message<P> message, ByteBuf outputBuffer) {
        outputBuffer.writeBytes(encodeInternal(message));
    }


    protected abstract List<Message<P>> decodeInternal(ByteBuffer nioBuffer);

    protected abstract ByteBuffer encodeInternal(Message<P> message);

}
